Proto-Oncogenes and Cell Cycle Gene Expression in Normal and Neoplastic Oral Epithelial Cells Stimulated With Soluble Factors From Single and Dual Biofilms of Candida albicans and Staphylococcus aureus .

This study was aimed at analyzing proto-oncogenic signaling pathway activation in normal oral keratinocytes (NOK-si) and neoplastic cell lines (SCC 25 and Detroit 562) stimulated with metabolites (soluble factors) from single and dual biofilms of Candida albicans and Staphylococcus aureus . Soluble factors (SF) from early (16-h) and mature (36-h) biofilms of C. albicans and S. aureus were collected and incubated with cell cultures, which were subsequently evaluated using gene expression via RT-qPCR, cell viability via AlamarBlue ^TM , and flow cytometry cell cycle analysis. In general, exposure to the SF of early and mature biofilms from C. albicans and dual species caused a major reduction in NOK-si cell viability and enhanced the sub G0 phase. This led to a decrease in gene expression. However, in this cell line, SF of S. aureus biofilms upregulated the CDKN1A gene followed by the maintenance of cell viability and a significant increase in the G2/M population. For tumor cells, SCC 25 and Detroit 562, the stimuli of SF biofilms upregulated oncogenes such as hRAS and mTOR , as well as Bcl-2 and CDKN1A . SCC 25 and Detroit 562 cells could survive even after 24 h of stimuli from both SF (early and mature). This occurred without significant changes taking place in the cell cycle progression for SCC 25, and with a significant tendency to increase the G2/M phase for Detroit 562. These results point to the fact that metabolites from prevalent clinical fungal and bacterial biofilms, C. albicans and S. aureus , can disrupt the homeostasis of normal and neoplastic oral epithelial cells. This changes proto-oncogenes' expression, specifically PI3KCA , hRAS , mTOR , BRAF , and cell cycle genes CDKN1A and Bcl-2 , thus causing a disturbance in cell viability, survival, and the cell cycle profile.
Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
(Copyright © 2021 Amaya Arbeláez, de Paula e Silva, Navegante, Valente, Barbugli and Vergani.)